This invention relates to simulation networks and more particularly to a network for simulating an inductor or resistor alone or connected in series.
In order to provide high-quality filters for use in integrated circuit applications, simulation procedures are employed to replace filter inductors with other elements than can be fabricated with integrated circuit techniques. Prior-art publications describe various networks for producing simulated inductors. In many instances, this is accomplished with a gyrator and a capacitor. The article "High-Quality Transistorized Gyrator" by D. F. Sheahan and H. J. Orchard, Electronics Letters, 1966, pp. 274 - 275, realizes a gyrator in terms of current generators. The article "Simulated Inductors Using Differential Amplifiers" by R. H. S. Riordan, Electronic Letters, February 1967, vol. 3, no. 2, pp. 50 - 51, describes a simulation circuit based on differential amplifiers since they are generally easier to realize than current generators. Although the Riordan circuit may be employed to produce both grounded and floating inductors, this circuit requires at least a pair of differential amplifiers as does the high-Q circuit in the article, "Active Filters and Oscillators Using Simulated Inductance" by R. L. Ford & F. E. J. Girling, Electronic Letters, February 1966, vol. 2, no. 2, p. 52. The article, "Loss-Compensated Active Gyrator Using Differential-Input Operational Amplifiers" by A. J. Prescott, Electronic Letters, July 1966, vol. 2, no. 7, pp. 283 - 284 discloses a circuit for simulating an ideal inductor with a single differential amplifier and a negative resistor, the latter also requiring an amplifier for simulation. Therefore two amplifiers are needed for Prescotts inductor simulation circuit.
An object of this invention is the provision of an improved network that uses a single amplifier, a single capacitor and positive resistors for simulating a grounded inductor and a resistor singularly or connected in series.